Critical care medicine specialists (also called intensivists) are medical doctors who specialize in the care of people who are in an intensive care unit (ICU).

In some areas, when a person is very ill and has to spend time in an ICU, he or she is cared for by a critical care medicine specialist. After the person is transferred out of the ICU to a regular hospital unit, another doctor or health professional assumes care.

Most critical care specialists are pulmonologists (specializing in lung disease) or cardiologists (specializing in heart disease). Critical care specialists may also first specialize in anesthesiology, internal medicine, neurological surgery, pediatrics, or surgery and then hold a subspecialist certificate in critical care medicine.

Critical care medicine specialists can be board-certified through the Boards of Anesthesiology, Internal Medicine, or Pediatrics, which are all recognized by the American Board of Medical Specialties.